The U.S. Geological Survey’s Water Availability and Use Study Program (WAUSP) (https://water.usgs.gov/ogw/gwrp/activities/regional.html) supports quantitative assessments of groundwater availability in areas of critical importance. As part of a WAUSP study in the arid to semi-arid Northwest Volcanic Aquifer Study Area (NVASA), estimates of runoff and baseflow were determined for 312 streamflow-gaging stations from 1904 to 2015. Gages with complete water years (October to September) of continuous-streamflow record were used to partition streamflow into runoff and baseflow, which is that part of streamflow attributed to groundwater discharge. For each water year annual estimates of baseflow, runoff, and a base-flow index were determined using a series of automated hydrograph separation programs—PART, HYSEP, and BFI. These streamflow-hydrograph analysis methods are available in the U.S. Geological Survey Groundwater Toolbox (https://water.usgs.gov/ogw/gwtoolbox/), which is a graphical, mapping and analysis interface built within an open-source MapWindow geography information system in a Windows computing environment.

The U.S. Geological Survey’s Water Availability and Use Study Program (WAUSP) (https://water.usgs.gov/ogw/gwrp/activities/regional.html) supports quantitative assessments of groundwater availability in areas of critical importance. As part of a WAUSP study in the arid to semi-arid Northwest Volcanic Aquifer Study Area (NVASA), estimates of runoff and baseflow were determined for 312 streamflow-gaging stations from 1904 to 2015. Gages with complete water years (October to September) of continuous-streamflow record were used to partition streamflow into runoff and baseflow, which is that part of streamflow attributed to groundwater discharge. For each water year annual estimates of baseflow, runoff, and a base-flow index were determined using a series of automated hydrograph separation programs—PART, HYSEP, and BFI. These streamflow-hydrograph analysis methods are available in the U.S. Geological Survey Groundwater Toolbox (https://water.usgs.gov/ogw/gwtoolbox/), which is a graphical, mapping and analysis interface built within an open-source MapWindow geography information system in a Windows computing environment.

The U.S. Geological Survey’s Water Availability and Use Study Program (WAUSP) (https://water.usgs.gov/ogw/gwrp/activities/regional.html) supports quantitative assessments of groundwater availability in areas of critical importance. As part of a WAUSP study in the arid to semi-arid Northwest Volcanic Aquifer Study Area (NVASA), estimates of runoff and baseflow were determined for 312 streamflow-gaging stations from 1904 to 2015. Gages with complete water years (October to September) of continuous-streamflow record were used to partition streamflow into runoff and baseflow, which is that part of streamflow attributed to groundwater discharge. For each water year annual estimates of baseflow, runoff, and a base-flow index were determined using a series of automated hydrograph separation programs—PART, HYSEP, and BFI. These streamflow-hydrograph analysis methods are available in the U.S. Geological Survey Groundwater Toolbox (https://water.usgs.gov/ogw/gwtoolbox/), which is a graphical, mapping and analysis interface built within an open-source MapWindow geography information system in a Windows computing environment.

The U.S. Geological Survey’s Water Availability and Use Study Program (WAUSP) (https://water.usgs.gov/ogw/gwrp/activities/regional.html) supports quantitative assessments of groundwater availability in areas of critical importance. As part of a WAUSP study in the arid to semi-arid Northwest Volcanic Aquifer Study Area (NVASA), estimates of runoff and baseflow were determined for 312 streamflow-gaging stations from 1904 to 2015. Gages with complete water years (October to September) of continuous-streamflow record were used to partition streamflow into runoff and baseflow, which is that part of streamflow attributed to groundwater discharge. For each water year annual estimates of baseflow, runoff, and a base-flow index were determined using a series of automated hydrograph separation programs—PART, HYSEP, and BFI. These streamflow-hydrograph analysis methods are available in the U.S. Geological Survey Groundwater Toolbox (https://water.usgs.gov/ogw/gwtoolbox/), which is a graphical, mapping and analysis interface built within an open-source MapWindow geography information system in a Windows computing environment.

The U.S. Geological Survey’s Water Availability and Use Study Program (WAUSP) (https://water.usgs.gov/ogw/gwrp/activities/regional.html) supports quantitative assessments of groundwater availability in areas of critical importance. As part of a WAUSP study in the arid to semi-arid Northwest Volcanic Aquifer Study Area (NVASA), estimates of runoff and baseflow were determined for 312 streamflow-gaging stations from 1904 to 2015. Gages with complete water years (October to September) of continuous-streamflow record were used to partition streamflow into runoff and baseflow, which is that part of streamflow attributed to groundwater discharge. For each water year annual estimates of baseflow, runoff, and a base-flow index were determined using a series of automated hydrograph separation programs—PART, HYSEP, and BFI. These streamflow-hydrograph analysis methods are available in the U.S. Geological Survey Groundwater Toolbox (https://water.usgs.gov/ogw/gwtoolbox/), which is a graphical, mapping and analysis interface built within an open-source MapWindow geography information system in a Windows computing environment.

The U.S. Geological Survey’s Water Availability and Use Study Program (WAUSP) (https://water.usgs.gov/ogw/gwrp/activities/regional.html) supports quantitative assessments of groundwater availability in areas of critical importance. As part of a WAUSP study in the arid to semi-arid Northwest Volcanic Aquifer Study Area (NVASA), estimates of runoff and baseflow were determined for 312 streamflow-gaging stations from 1904 to 2015. Gages with complete water years (October to September) of continuous-streamflow record were used to partition streamflow into runoff and baseflow, which is that part of streamflow attributed to groundwater discharge. For each water year annual estimates of baseflow, runoff, and a base-flow index were determined using a series of automated hydrograph separation programs—PART, HYSEP, and BFI. These streamflow-hydrograph analysis methods are available in the U.S. Geological Survey Groundwater Toolbox (https://water.usgs.gov/ogw/gwtoolbox/), which is a graphical, mapping and analysis interface built within an open-source MapWindow geography information system in a Windows computing environment.

The U.S. Geological Survey’s Water Availability and Use Study Program (WAUSP) (https://water.usgs.gov/ogw/gwrp/activities/regional.html) supports quantitative assessments of groundwater availability in areas of critical importance. As part of a WAUSP study in the arid to semi-arid Northwest Volcanic Aquifer Study Area (NVASA), estimates of runoff and baseflow were determined for 312 streamflow-gaging stations from 1904 to 2015. Gages with complete water years (October to September) of continuous-streamflow record were used to partition streamflow into runoff and baseflow, which is that part of streamflow attributed to groundwater discharge. For each water year annual estimates of baseflow, runoff, and a base-flow index were determined using a series of automated hydrograph separation programs—PART, HYSEP, and BFI. These streamflow-hydrograph analysis methods are available in the U.S. Geological Survey Groundwater Toolbox (https://water.usgs.gov/ogw/gwtoolbox/), which is a graphical, mapping and analysis interface built within an open-source MapWindow geography information system in a Windows computing environment.

The U.S. Geological Survey’s Water Availability and Use Study Program (WAUSP) (https://water.usgs.gov/ogw/gwrp/activities/regional.html) supports quantitative assessments of groundwater availability in areas of critical importance. As part of a WAUSP study in the arid to semi-arid Northwest Volcanic Aquifer Study Area (NVASA), estimates of runoff and baseflow were determined for 312 streamflow-gaging stations from 1904 to 2015. Gages with complete water years (October to September) of continuous-streamflow record were used to partition streamflow into runoff and baseflow, which is that part of streamflow attributed to groundwater discharge. For each water year annual estimates of baseflow, runoff, and a base-flow index were determined using a series of automated hydrograph separation programs—PART, HYSEP, and BFI. These streamflow-hydrograph analysis methods are available in the U.S. Geological Survey Groundwater Toolbox (https://water.usgs.gov/ogw/gwtoolbox/), which is a graphical, mapping and analysis interface built within an open-source MapWindow geography information system in a Windows computing environment.

The U.S. Geological Survey’s Water Availability and Use Study Program (WAUSP) (https://water.usgs.gov/ogw/gwrp/activities/regional.html) supports quantitative assessments of groundwater availability in areas of critical importance. As part of a WAUSP study in the arid to semi-arid Northwest Volcanic Aquifer Study Area (NVASA), estimates of runoff and baseflow were determined for 312 streamflow-gaging stations from 1904 to 2015. Gages with complete water years (October to September) of continuous-streamflow record were used to partition streamflow into runoff and baseflow, which is that part of streamflow attributed to groundwater discharge. For each water year annual estimates of baseflow, runoff, and a base-flow index were determined using a series of automated hydrograph separation programs—PART, HYSEP, and BFI. These streamflow-hydrograph analysis methods are available in the U.S. Geological Survey Groundwater Toolbox (https://water.usgs.gov/ogw/gwtoolbox/), which is a graphical, mapping and analysis interface built within an open-source MapWindow geography information system in a Windows computing environment.

This data release contains drainage basin characteristics and peak-streamflow trend and change-point results for 2,683 U.S. Geological Survey (USGS) streamgages in the conterminous U.S. Data include streamgage identification number, name, drainage area, latitude, longitude, percent urban land use, dam storage, streamgage classification, record completeness status, lag-1 autocorrelation, trend slopes and significance, peaks-over-threshold counts, trends in the numbers of peaks-over-threshold, and change point years and values for median and scale. Also included is an R script containing the Mann-Kendall trend test for three different null hypotheses of the serial structure of the time-series data: independence, short-term persistence, and long-term persistence. Revised - April 8, 2019 (ver. 3.0).